Urea ammonium nitrate (UAN) is an aqueous solution of urea and ammonium nitrate and is used as fertilizer. A process for producing UAN generally comprises producing ammonium nitrate in an ammonium nitrate section (AN production section), forming urea in a urea production unit, and combining said produced ammonium nitrate and urea to produce urea ammonium nitrate in a urea ammonium nitrate section (UAN production section).
The production of ammonium nitrate solution involves the neutralisation reaction of gaseous ammonia with concentrated nitric acid solution according to the following reaction:HNO3+NH3→NH4NO3 
The production of ammonium nitrate solution generally results in an off-gas (AN off-gas), in particular from the neutralization reaction of ammonia with nitric acid. Because the formation of ammonium nitrate is a highly exothermic reaction, the AN off-gas generally comprises water vapor, residual ammonia and entrained droplets from the reaction medium. The droplets can comprise ammonium nitrate and/or nitric acid. Accordingly, AN off-gas may for instance comprise CO2, NH3, water, ammonium nitrate, N2, O2 and nitric acid. The AN off-gas is usually subjected to condensation and the condensate is for instance passed in part to the UAN production section.
Some general desires for improving a process comprising producing UAN include reducing steam consumption (increasing energy efficiency) and reducing emissions and emission points, in particular of ammonia. It is also desired to reduce waste streams, improve product recovery and reduce the amount of make-up water and acid used for scrubbing. Such advantages are desirably obtained for new plants (grass-roots plants) as well as by modifying or revamping existing plants. Equipment costs and other capital expenditures are preferably minimized.